Rotary concentric partition in a coke oven hearth



June 3, 1969 v. D. ALLRED 3,448,012 ROTARY CONCENTRIC PARTITION IN ACOKE OVEN HEARTH Filed Feb. 1, 1967 Sheet of 2 IN N FIG. I

INVENTOR VICTOR DEAN ALLRED v. D. ALLRED 3,448,012 ROTARY CONCENTRICPARTITION IN A COKE OVEN HEARTH June 3, 1969 Sheet Filed Feb FIG. 2

INVENTOR VICTOR DEAN ALLRED United States Patent 3,448,012 ROTARYCONCENTRIC PARTITION IN A COKE OVEN HEARTH Victor D. Allred, Littleton,Colo., assignor to Marathon Oil Company, Findlay, Ohio, a corporation ofOhio Filed Feb. 1, 1967, Ser. No. 613,145 Int. Cl. Cb 49/06, 37/00,47/18 US. Cl. 20127 9 Claims ABSTRACT OF THE DISCLOSURE A coke ovenchamber is comprised of a conical hearth with an outlet at the centerand lowermost portion. An overlying rotary cap has spaced rabblesdepending therefrom disposed to move material on the hearthprogressivelyinwardly towards the material outlet. The cap is furtherprovided with a cylindrical partition depending from it and coaxial withthe outlet. The partition extends into a bed of material on the hearth.

BACKGROUND OF THE INVENTION Field of the invention 'mixed in the form ofbriquettes or other cohesive shapes.

Description of the prior art The present invention devolatilizes thematerial being treated by the direct application of heat to the materialpreferably or largely through radiation from the roof and side walls ofthe devolatilizingchamber, such heat being supplied by oxidation withinthe chamber of the oxidizable volatile matter being continuously drivenoff by the material being treated, and in addition the present:invention provides a plurality of zones substantially gas type one fromthe other within said heating chamber so that various temperatures canbe maintained within a single furnace while the material is free to movefrom one zone to another under the action of plow-like rabbles whichmove relative to the hearth of the furnace. The

simplicity of the process and apparatus of the present invention is inmarked contrast to the closed pots, containers or cars moved throughheating chambers which have been used heretofore.

SUMMARY OF THE INVENTION The present invention is to be limited only bythe claims appendedhereto and the abstracts, examples and summariesincluded within the present disclosure are to be taken as being merelyillustrative of the invention.

However, the invention offers apparatus and means for providing avariety of temperatures within a furnace which is at least partiallyheated by the oxidation of volatile matter which is removed from thematerial being treated through the action of heat. This profiledtemperature is highly useful where it is important that the materialsnot be thermally shocked. In such cases a relatively cool zone can bemaintained near the inlet to the furnace and materials can graduallypass under the partition means separating this zone from the next innerzone which can be maintained at a higher temperature and additionalsuccessive inner zones maintained at successively higher temperaturescan be provided until the treatment of the material is complete and thematerial drops through an outlet located at or near the center of thehearth.

The materials being treated are preferably moved through the furnaces ofthe present invention by means of rabbles which operate like plows andwhich move relative to a hearth, preferably imperforate, so as todistribute the material on the hearth in a series of preferablyconcentric furrows which are turned over wholly or partially by eachpass of the rabbles through the bed. The zones of different temperaturescan be separated by providing partition means, preferably curtain walls,which are attached in substantially gas impervious, mechanically fixedrelationship to the top or outer walls of the furnace chamber and whichextend downward to a point near the top of the bed so as to permitmovement of the bed under the partition means while preventing majorflow of gases from one zone to another. The temperatures within thezones may be controlled either by the autogenous process of reducingvolatiles and oxidizing them within each of the zones at a ratesufiicient to give the temperature desired in each particular zone.Alternatively, burners or cooling means such as cold air blowers can beprovided to control the temperatures within the various zones.Particularly preferred are processes where, as the zones becomeprogressively hotter, more volatiles are removed from the material inthe inner zones so as to maintain a higher temperature in those zonesand exhaust gases from the inner zones are conducted through at least aportion of the outer zones where they may be mixed with air or otherwisecontrolled to give lower temperatures in such outer zones. The flow ofgases to the outer zones may be either cocurrent or concurrent with themovement of the material on thebed.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a vertical section througha furnace according to the present invention;

FIGURE 2 is an enlarged detailed view showing the rabbles, and thepartition means of FIGURE 1;

FIGURE 3 is a planned detailed view of a portion of the hearth showingthe rabbles and curtain walls.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGURE 1 shows a furnace havinga rotary hearth 10 with an inner hearth surface 11 sloping from theouter periphery downwardly to a central axially extending soaking pit 12integral with and depending from the hearth 10. The rotary hearth 10 issupported on spaced rollers 13 mounted on a furnace frame 14. The hearthis rotated by a motor and a rack and pinion drive in a conventionalmanner for rotary hearth furnaces. A curb 15 extends vertically abovethe hearths surface 11 at its outer periphery and carries a waterseal 16filled with water 17. Sand, fluid coke, or similar pulverized materialcan be used instead of water, if preferred.

The furnace frame 14 carries roof beams 20 which support a castrefractory roof 21 having a central flue 22. The roof 21 has a dependingwall 23 carrying flange 24 which extends into the water 17 carried inwater seal 16. The roof 21 is provided with wickets or nozzles 27 whichreceive air from duct 26 mounted on the furnace frame 14. The ports 27direct gases gently downward toward the hearth. Top 21 and side walls 23of the roof are provided with ports 27 receiving air from duct 26. Theports 27 direct air across the hearth in a radial direction. In aparticular preferred embodiment shown in FIGURE 1 all of the ports 27direct air into the inner chamber 60 which is separated from the outerchamber 61 by a refractory curtain wall 62 which extends downward fromthe room 21 to a point about six inches above the interior hearthsurface Patented June 3, 1969 I 11. This curtain wall 62 extendsconcentrically all around the hearth so as to substantially completelyseparate the inner chamber 60 from the outer chamber 61 excepting onlythe notch 68 between the lower edge of the curtain Wall and the innerhearth surface 11. (In other embodiments a wall which only separates asegment of the furnace could be used.)

Burners 29 (not shown) are provided in the roof of the inner chamber tobring the furnace to operating temperature and to provide additionalheat for those reactions which are not completely autogenetic. A feedchute 30 passes through the roof 21 adjacent the side wall 23 and isprovided with a vertically adjustable delivery end 31 extending to apoint adjustably selected to deliver a selected thickness of feed ontohearth surface 11. A radially extending U-shaped rabble pit 32 (shown inFIGURE 2) is formed in the roof and extends radially from the fine 22 tothe roof wall 23. The bottom of this pit 32 is provided with slotsadapted to slidably receive rabbles 34. Rabbles 34 may be solid or ofhollow platelike structure with inner vertical baflles depending uponthe temperature involved. For the higher temperatures, of course, thelatter is preferred. Each bathe is provided with inlet and outletcoolant conduits which also act as supports for the rabbles. Coolantsuch as water or air is delivered to the inlet and into rabble 34 on oneside of the baflle and then under the baflie to the opposite side of therabble and out through the outlet pipe 37. Refractory seals 38 areprovided on conduits 36 and 37 to fit within slot 33. The conduits 36and 37 are held between two angular rabble holders which are heldtogether by bolts. The rabble holders 39 and 40 are fastened betweenadjustable carrier angle beams and by bolts. Vertical adjustment screwsare provided at each end of each adjustable carrier beam. These screwsbear on fixed rabble beams which extend across the rabble pit 32 asshown in FIGURE 3 and serve to vary the currents between the lower endof the rabbles 34 and the interior surface of the hearth 11.

A rotary discharge table 50 is provided beneath the soaking pit 12 toreceive the output of the furnace. A fixed discharge spout of plow 51 ismounted in frame 14 between the soaking pit 12 and discharge table 50with spout 51 is provided with a peripheral trough 52 carrying sand 53into which a depending flange 54 on the soaking pit extends to form aseal.

The operation of the furnace described above is as follows. The burners29 are fired to bring the furnace up to the desired temperature whichdepends upon the nature of the material being devolatilized or calcined.Material to be treated is fed through feed chute 30 and is continuouslyspread to the desired thickness and width along the outer periphery ofhearth surface 11. As the hearth rotates the material encounters therabbles 34. Each set of rabbles deflects materials striking it into thenext adjacent concentric furrow ring so that the flow of material fromthe periphery of the hearth surface 11 to the soaking pit 12 isgenerally in spiral concentric rings, each of greater width so that asthe rings become smaller the area becomes greater providing a uniformdepth. Material moves under the curtain Wall 62 through a notch 68 inits lower edge so positioned as to receive material from one of therabbles 34. These concentric spiral rings are diagrammaticallyillustrated in FIGURE 3, together with the relative position of eachrabble with respect to such rings. The vertical position of the rabblesdetermines the residual amount of material which is to be left on eachring as the hearth rotates. The rabbles tend to cause mixing andinversion of the bed several times as the material moves downwardly fromthe hearth periphery to the soaking pit. This permits more uniformheating and provides a more uniform product and is an importantattribute of the present invention.

Exhaust gases exit through fine 22 or may be partially diverted throughconduit 64 past adjustable damper 65 and downward into the outer chamber61. The exhaust gases then flow substantially circumferentially through4 outer chamber 61 until they reach a second flue 66 from which theyexit. Gases exiting from flue 66 may be conveyed back to mix with gasesfrom flue 22 or separate stacks or other venting points may be providedfor each of the flues.

To even further enhance this mixing the hearth may be arranged in aseries of steps like a circular amphitheater so that the rabbles pushmaterial ofl? one step and cause it to cascade down to the next stepwhere the next rabble then pushes it to a succeeding lower step, etc.This method is especially advantageous where a large amount of fines areinvolved and where such fines must frequently be brought to the uppersurface of the bed in order to achieve product uniformity.

It will be understood that the invention is susceptible to a widevariety of modifications and variations many of which will be obvious tothose skilled in the art. For example, it is possible to have variousconfigurations of rabbles other than the flat quadrangular rabblesillustrated e.g. mold boards or conventional plow designs may beutilized where desired. Another important variation is that the damper65 in conduit 64 may be completely closed on conduit 64 completelyeliminated so that no gases flow from the inner chamber to the outerchamber. Each chamber will then be under a temperature which isdetermined by the amount of volatile matter released and consumed andthis temperature may be varied by varying the rate of heat of oxygen ormay be varied by the operation of burners in either or both of the innerand outer chambers 60 and 61. It should be also understood that thenumber of chambers need not be confined to two and that the inventionmay be practiced with a number of concentric curtain walls dividing thefurnace interior into a number of individual zones, each being operatedat a different temperature.

Thermostatic and other automatic controls may of course, be utilized forthe control of hearth rotation, temperature within the individual zones,cross flow of gases through conduits from one zone to another, etc.Likewise, the applications of the furnaces of the present invention aremany and varied. However, it should be noted that among the mostpreferred applications of the invention are its use in first drying andthen calcining raw coke, especially petroleum coke which is frequentlywet with 10% or more by weight of water during its process ofmanufacture. The drying may be accomplished in the outer zone attemperatures which are not sufiicient to devolatilize such petroleumcoke to any substantial degree, e.g. temperatures below about 500 F. Athigher temperatures, e.g. above about 2000 degrees F. maintained Withinthe inner chamber, the coke may be calcined by the methods of thepresent invention with all of its attendant thorough mixing and uniformquality of product. Exhaust gases from one zone can be used to heatother gases, e.g. air in a suitable gas-to-gas heat exchange and suchother gases may be conducted into a second zone. These, and all othermodifications which are obvious to those skilled in the art upon areading of the present application, are to be taken as being includedwithin the claims appended hereto.

What is claimed is:

1. An oven comprising a heated chamber, a hearth located in the chamber,a material outlet at the center of the hearth, means for deliveringmaterial to the hearth adjacent the outer periphery thereof to form abed of material on the hearth, spaced rabbles disposed above the hearthand disposed to move material on the hearth progressively inwardlytoward the material outlet upon relative movement between the hearth andthe rabbles, at least one substantially cylindrical partition meanscoaxial with the hearth center dividing said chamber into at least oneinner zone and at least one outer zone, said partition means havingupper and lower edges, the upper edge of said partition means beingconnected to the wall enclosing said chamber so as to form a sealsubstantially impervious to gases and mechanically fixed to said chamberwall, said partition means extending downwardly toward said hearth andterminating in a lower edge substantially parallel to said bed anddisposed close to the top of said bed, and wherein an exhaust exit forgases is provided from at least one inner zone and conduit meansconnects said exhaust means to an inlet in at least one outer zone sothat exhaust gases from said inner zone or gases heated by said exhaustgases flow through at least a portion of said outer zone, wherebymaterial on the hearth moves progressively inwardly passingsubstantially under said partition means and whereby only minor flow ofgases between said inner and said outer chamber occurs between the topof said bed and the lower edge of said partition means.

2. The oven of claim 1 in which the hearth is substantially horizontaland imperforate.

3. The oven of claim 1 in which the hearth is substantially horizontaland imperforate.

4. A process for devolatilizing material which yields oxidizablevolatile matter under heat continuously comprising the steps of (a)continuously delivering the material to be treated onto a hearth in anouter zone of a heated oven chamber adjacent the outer periphery thereofto form a bed thereon,

(b) relatively moving the hearth and the material thereon with respectto a plurality of spaced rabbles disposed above the hearth,

(c) progressively advancing the material toward a material outlet at thecenter of the hearth by disposing said rabbles such that they extendinto the bed at an angle of attack that moves the bed propressivelyinwardly toward said material outlet,

(d) turning the bed over and over during its progressive movement towardthe material outlet,

(e) moving the bed under a partition means which separates said outerzone from an inner zone also located within said heated oven chamber,discharging the treated material into a material outlet located withinsaid inner zone substantially at the center of the hearth,

(f) burning at least a portion of said volatiles within said inner zone.

5. The process of claim 4 wherein gases evolve from said inner chamber,are conducted through at least a portion of said outer chamber, andwherein said outer chamber is maintained at a temperature substantiallylower than the temperature within said inner chamber.

6. The process of claim 5 wherein the temperature in said outer chamberis sufficiently low so as not to heat said bed to a temperature aboveabout 500 degrees F. and wherein the temperature Within said innerchamber is above about 2,000 degrees F.

7. The process of claim 6 wherein the hearth rotates substantially aboutits center point and wherein gases from said inner zone are conveyedthrough at least a portion of said outer zone in a direction concurrentto the rotation of said hearth.

8. The process of claim 6 wherein said hearth rotates substantiallyabout its center point and wherein gases from said inner zone areconveyed through at least a portion of said outer zone in a directioncocurrent to the rotation of said hearth.

9. The oven of claim 1 comprising a plurality of partition meansdividing said heated chamber into at least three zones.

References Cited UNITED STATES PATENTS 151,640 6/1874 Wheelwright202-103 985,053 2/1911 Noad 202103 1,878,581 9/1932 Ab-der-halden202-104 2,676,006 4/1954 Martin 26326 NORMAN YUDKOFF, Primary Examiner.D. EDWARDS, Assistant Examiner.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,448,012 June 3, 1969 Victor D. Allred It is certified that errorappears in the above identified patent and that said Letters Patent arehereby corrected as shown below:

Column 5, line 18: Delete "1" and substitute therefor Signed and sealedthis 4th day of November 1969.

(SEAL) Attest:

Edward M. Fletcher, Jr. E. SCHUYLER, JR.

Attesting Officer Commissioner of Patents

